The present invention concerns a lifting equipment for an offshore construction of a floatable platform with raisable and lowerable support legs bearing directly or indirectly on the sea bed. At least two cable winches for each support leg are arranged on the platform. One cable winch is connected through a single cable line with the lower end of a support leg and the other cable winch displays a multiple cable line guided around two pulley blocks, one of which is arranged on the support leg.
Such a lifting equipment is related subject matter of the German Patent Application No. 3 008 585. By this lifting equipment, it is possible during the erection of the offshore construction to put the support legs down free of shock or substantially free of shock even when the sea is not quiet. For this, the lifting equipment is constructed in such a manner that it is blocked against a downwardly directed movement caused by the motion of the sea each time, when with the support legs touching down and the platform floating, this is disposed just at the highest point of the wave motion. In that case, the drive of the one cable winch is switched off, while the other cable winch is freed in spooling direction and the unspooling direction is blocked. In order to be able to lift the weight of the platform, which can amount to 20,000 to 40,000 tons, a cable winch with a multiple cable line must be used. At small depths of water or on the use of a sub-structure, which has been previously lowered onto the sea bed and onto which the support legs touch down, the lift to be exerted by the cable winch and thereby the cable length even with a multiple cable line is comparatively small. For great lengths of the support legs of 100 meters, for example, the required cable lengths are no longer to be managed in the case of a multiply-guided cable line.